My G3 swap timeline has always been winter of 2023/24. That was more because I have to do the T56/TR6060 swap at the same time and I didn't expect to buy the trans until next summer.
But all along the way I have been buying up the parts I needed just so I didn't get to the point of being ready and either they are unavailable or on back order. Took 3 months to get my headers, and if I hadn't been told there were pans on eBay I would still be waiting on that. I still need a car front cover and things like gaskets and such. Best I know, the only part I am nervous about is the lifters, but I have my 6.4 cam and upgraded valve springs already. And I even pulled the trigger on a "Black Friday" deal for a T56 and am just waiting on that to arrive.
In theory, I could actually start in January. But the reality is that there are probably things I am missing and a fair amount of money left to spend and if I did jump into it this winter it could end up keeping the car off the road this summer. And I want to avoid that at all cost. Never know, but I expect I will just keep buying parts, put my core 5.7 together and wait until the winter of 2023 to start the swap.
